The US equity market is experiencing significant structural changes, including updates to market data, regulations, and trading methods. In November 2025, major regulatory changes were introduced, affecting how market participants trade and view data for listed equities, notably altering lot sizes based on traded price. These changes include adjustments to round lots, with different sizes set according to the average closing price of securities, impacting around 250 stocks, including Tesla and Meta. The changes have reduced the percentage of odd lot trades and altered the perception of liquidity, although the underlying liquidity remains constant.
Additionally, the growth of overnight trading has been notable, with exchanges offering extended hours and ATS venues like Blue Ocean leading in trading volumes, driven by Asian markets. The introduction of fractional share reporting and dynamic tick sizes in 2026 will demand more granular data analysis. Understanding these changes is crucial for market participants to adapt to the evolving landscape, focusing on depth, odd lots, and overnight trading patterns. The transition will require leveraging detailed data to ensure accurate analysis and effective trading strategies.
